Automatic pencil sharpener



May 29, 1923.

H. M. MITCHELL AUTOMATIC PENCIL SHARPENER 2 sheets-sheet 1 Filed June 19, 1922 jffl 7 m: ELL

36 7/,\\\\\\\\\\\llllllllllllllllllIII/IIZ/ I May 29, 1923. 1,456,904

H. M. MITCHELL AUTOMAT I C PENC I L SHARPENER Filed June 19, 1922 2 Sheets-Sheet 2 F 225; lei

Affaz me figu Patented May 29,1923.

UNITED STATES HARLAN M. MITCHELL, OF SAN FRANCISCO, CALIFOTENIA.

AUTOMATIC PENCIL SHABPENEB.

Application filed June 19, 1922. Seriallo. 589,197.

To all whom it may concern:

Be it known that I, HARLAN M. MITCHELL, a citizen of the United States, and resident of San Francisco, county of San Francisco, State of California, have invented a new and useful Automatic Pencil Sharpener, of which the following is a specification,

The present invention relates to improvements in pencil sharpeners and its particular object is to provide an economic and convenient means for sharpening a pencil that will work automatically upon the insertion of the pencil and therefore may be used very much like an ink stand. A further object of the invention is to provide a pencil sharpener of the character described that may be selectively used for giving to the pencil either a chisel point such as Is preferably used by draftsmen, architects or engineers, or a needle point such as is used in everyday practice. A further object of the invention is to provide a pencil sharpener in which emery cloth is used for putting a fine point on the lead while automatic cutters are employed for removing the wood. Other objects and advantages of my device will appear as the specification proceeds.

With the above objects in view I have illustrated the preferred form of my invention in the accompanying drawings in which Figure 1 represents a side elevation of my device, partly shown in section, Figure 2 a top plan view f the same, Figure 3 a horizontal section through the same along line 3-3 of Figure 1; Fi re 4 a horizontal section along line 44 0 Figure 1; Figure 5 a horizontal section along line 5-5 of Figure 1; Figure 6 a detail view in plan of an upper holding member for the cutters in m device; Figure 7 a cross section through t e same along line 77 of Figure 6; Figure 8 a detail view in plan of a lower holding member for the cutters; Figure 9 a cross section through the same along line 9--9 of Figure 8; Figure 10 a detail plan view of an internally toothed gear; Figure 11 a cross section through the same along line 11-11 of Figure 10; Figure 12a vertical section through an upper portion of the device taken along line 1212 of Figure 2; Figure 13a detail view in end elevation of a slide supporting the emery cloth; Figure 14 a plan view of the same; Figure 15 a side elevation of the same; Figure 16 a detail view of a guiding member for the slide; Figure 17 an end elevation of the same; Figure 18 is a side view of the same; Figure 19 a plan view of the sharpening mechanism assembled; Figure 20 a plan position, and Figure 21 a perspective view of a piece of emery cloth. While I have shown only the preferred form of my inventlon, I wish to have it understood that various changes or modifications might be made within the scope of the claims hereto attached without departing from the spirit of the invention.

The housing (1) of my device is preferably of cylindrical form, the bottom end (2) and the top (3) being closed as shown in the drawing. In operative proximity to the top plate (3) is mounted, a second plate (4) the two plates serving as a hearing for the hollow shaft (6) shown in detail in Figures (6) and (7 and provided at its lower end with a gear (8) and a disc (9). This hollow shaft serves as the upper supporting member for three cutters (11) arranged s mmetrically around a central line in sli ing relation in a manner well known in the art. The lower support or bearing (12) for these three cutting members is shown in detail in Figures (8) and (9) and is provided with a slightly conical upper surface (13), and annular groove (14) around its central portion and beveled gear teeth (16) at its bottom. Suitable holes (17) in the upper bearing and (18) in the lower bearing are provided to receive the respective shafts of the cutters. A horizontal plate (19) engaging the annular groove (14) serves as a centering device for the cutters.

Rotary motion is imparted to the cutting mechanism thus far described by the spiral spring (21) supported by the two plates (3) and (4) and having one end (22) secured to a pin (23) extending, between the two plates while its other end engages the hollow shaft (6) as shown at 24). This spring may be wound by means of the handle (26) secured to the disc (27 which latter engages through a downwardly extending shaft (28), the hollow shaft (6) by means of ratchet teeth (29). As shown in Figure (2) the disc (27) is also provided with circumferential ratchet teeth (31) adapted to be engaged by the pawl View of the same mechanism in a different (32) which allows of rotary motion in one direction only and is kept in engagement with the teeth by the spring (33).

An internally toothed gear wheel (36) is .rigidly supported by means of arms (37) underneath the plate (4) so as to operatively engage cog wheels (38) fixed to the cutters (11) in coaxial relation to the same and to rotate the cutters on their own axes while they revolve around a central axis.

The device thus far described operates as follows: the spring is set by turning the handle (26) clock-wise as view d in Figure (1) and is maintained in that position by means of the pawl (32) engaging the ratchet (31). When a pencil is inserted between the three cutting elements and the latter are thereby pushed downwardly the engagement between the hollow shaft (6) and the shaft (28) associated with the handle is disconnected and the hollow shaft (6) allowed to rotate under the influence of the spiral spring (21). Since the hollow shaft (6), the cutters (11) and the lower supporting member (12) for the same form one unit, the whole mechanism is revolved around a central axis and the individual cutters are caused to rotate on their own axes due to the engagement of their cog wheels (38) with the internal gear (36).

Underneath this working mechanism are supported two plates (41) and (42) which provide a. bearing for a vertical shaft (43) supported in axial alignment with the center line of the working mechanism thus far described. The lower end of the shaft is received in a recess (44) in the bottom member (2) and yieldingly supported on the spring (46). The upper end of the shaft terminates in a beveled gear (47) meshing with two vertical beveled gears (48) and (49) su ported on horizontal shafts (51) and (52 journaled in the two arms (53) and (54) of a yoke (56) loosely mounted on the shaft (43), a loose collar (57) holding. .the yoke in spaced relation to the plate (41). Between the two fplates (41) and (42) a gear wheel (61) is xed to theshaft (43) which engages through an idler (62), a gear wheel (63) supported on the vertical shaft (64) to which latter is keyed another gear wheel (66) meshing with the gear wheel (8) on the hollow shaft (6). It will thus be seen that when the hollow shaft 6) is rotated the shaft (64) also rotates and the rotary motion is transmitted to the shaft (43), the meshing gears being of the same size so that the hollow shaft (6) and the shaft (43) rotate at the same speed.

The gear wheel (66) may be disengaged from the gear wheel 8) at the option of the operator by bending the shaft (64) which is made of spring steel and pulling its up er end to the left as illustrated in Figure i l) by means of the latch (67) which is provided with a small pin (68) adapted to engage either one of two perforations (69) and (71) in the top of the housing. The latch being made of spring material its far end can be readily lifted for the purpose of shifting the pin (68) from one perforation to the other. When the upper end of the shaft (64) is shifted to the left the gear wheel (66) engages a stud (72) supported underneath the plate (4) which prevents the gear wheel from rotating so that thereby the whole working mechanism including the beveled gear (47) The operator can thereby either allow the gear (47) to rotate at the same speed as the gear of the member (12) or he can stop the gear wheel (47) from rotating altogether. In the former case the two opposing gear wheels will rotate in opposite direction due to the introduction of the idler (62). When both gears rotate the two beveled gears (48) and (49) will be caused to rotate on their own axes but they-will not revolve around the center of the mechanism so that in this case the yoke (56) remains stationary. If however the gear wheel (47) is prevented from rotating then the beveled gears (48) and (49) will not only rotate on their own axes but they will also revolve on the center of the working mechanism, which latter is occupied by the point of the pencil.

The shafts (51) and (52) on which the beveled gears (48) and (49) are rotatably supported terminate at their inner ends in transverse guide members (76) shown in detail in Figures (16) (17) and (18), the two members being disposed horizontally, then bases (77) facing each other and then sides (78) tapering towards the top. On these guide members are supported the slides (81) shown in detail in Figures (13) (14) and (15) provided with a longitudinal groove (82) with tapering sides (83) adapted to receive the guide members (76), a slot (84) being provided to accommodate the shaft (51) when the slide reciprocates on the guide. Reciprocating motion is imparted to this slide by the beveled gear (48) through a pin (86) rising from the interior surface of the latter gear and engaging a transverse groove (87) in the slide. The operation should be readily understood by referrin to Figure (15). Assuming that the pin 86) engages the right hand side of the transverse slot and rotates clock-wise. the slide will first be forced forward until the pin has almost passed through a quarter revolution. t this time the pin will leave the transverse groove and pass into the longitudinal groove (82). While the pin passes through the longitudinal groove the slide is held stationary by means described hereinafter so that -when it strikes the opposite side of the longitudinal groove (82) it will find its way into the left hand side of the transverse is locked against rotation.

' readil groove (87) engage the same and on the continuation of its turning movement force the slide into the o osite direction. After passing through hal f a revolution the pin 15 again ready to leave the left hand side of the transverse groove in the slide and to pass through the longitudinal groove (82) into the right hand side'of the transverse groove.

so as to reverse the direction of the slide during the next half revolution. In this manner the slide will be reciprocated on the guide member. Special means are provided for holding the slide stationary while the in asses through the longitudinal groove. Riotlon in one direction is prevented by the end member (88) secured to the guide (76) at either end by means of a pin (89) penetrating a slot (91) in the end member which is struck by the slide at the end of each reciprocation and thereby prevents further motion in that direction. Motion in the opposite direction is prevented by a U shaped projection (92) rising from the inner surface of the gear (48) opposite the pin (86) and engaging one of the two studs (93) projecting from the surface of the slide. In this manner the slide is firmly held for an instant between the end member (88) secured to the guide and the U shaped member (92) engaging and passing around the stud (93) at the opposite end of the slide. When the pin (86) has passed through the longitudinal groove (82) and engaged one side or the other of the transverse groove (87) the U shaped member (92) becomes disengaged from the stud (93) and allows the slide to move in that direction.

The. two sides of the slide facin each other are slanted as is best shown in igure 1 to conform with the angle at which it is desired to sharpen the pencil. The two opposing sides are covered with emery cloth which is preferably shaped as shown in Figure (21), a body portion (9 1) covering the face of each slide while wings (96) bent upon themselves as shown at (97) are adapted to slidably engage clips (98) secured to the ends of the slide thus allowing of an easy and quick exchange of the emery cloth.

The operation of the device should be understood from the foregoing descri tlon. If a chisel point is desired the latch (67) is set with the pin (68) engaging the right hand perforation (71) (see Figure 12) so that all the gears are engaged. The gear wheels 17) and (16) then rotate at the same speed in opposite direction causing the bevels (48) and (49) to rotate on their own axes without revolving the yoke (56). The rotation of the bevels (48) and (49) causes the two slides (81) to reciprocate on their respective guides (76) so that their two working surfaces covered by emery cloth engage the point of the pencil and sharpen the same to resemble a chisel. If a including the beveled gear wheel (47). The

locking of this gear wheel does not interfere with the reciprocating motion of the two slides (81) and their respective guide members (76) but at the same time causes the two slides to rotate around the pencil point so as to sharpen the same to resemble a needle point.

I claim:

1. In a pencil sharpener of the character described a pair of sharpening elements enwaging the encil point on opposite sides, and means or reciprocating each of them comprising a guide, a slide thereon sunnortmg the sharpening member having a transverse groove therein, a rotary wheel. and a pin pro ecting from the latter engaging the groove in the slide.

2. In a pencil sharpener of the character described a pair of sharpening elements engaging the pencil point on opposite sides, and means for reciprocating each of them compris ng a shaft having a guide fixed thereto, a slide on the same supporting the sharpenmg member having a longitudinal groove for clearing the shaft and a transverse groove, a rotary wheel, a pin projecting from the latter engaging the transverse groove in the slide for reciprocating the same and means for holding the slide statlonary while the pin crosses the longitudinal groove. I

3. In a pencil sharpener of the character described a pair of sharpening elements engaging the pencil point on opposite sides, and means for reciprocating each. of them comprising a shaft having a guide fixed thereto, a slide on the same supporting the sharpening member having a longitudinal groove for clearing the shaft and a transverse groove, a rotary wheel, a pin project ing from the latter engaging the transverse groove in the slide for reciprocating the same and means for holding the slide stationary while the pin crosses the longitudinal groove, comprising a terminal stop preventing motion in one direction and co-acting projections on the wheel and the slide slidably engaging one another for prevent' ing motion in the other direction.

4. In a pencil sharpener of the character described, a pair of sharpening elements engaging the pencil point on op osite sides,

.means for reciprocating them and means for simultaneously rotating them around the pencil point.

5. In a pencil sharpener of the character described, a pair of sharpening elements en- I gaging the pencil point on opposite sides,

means for reciprocating them, means for simultaneously rotating them around the pencil point and. differential means for selec- 5 tively rendering the latter means active or inactive.

,6. In a pencil sharpener of the character described, a sharpening mechanism for the pencil, a spiral spring for actuating the same, a stationary ratchet, a second ratchet 10 tive.

' HARLAN M. MITCHELL. 

